Luggage is designed to store, transport, and protect possessions while a user is traveling. In its most basic form, a piece of luggage is simply an enclosure with an opening that may be opened and closed to place possessions into the interior of the luggage.
Today, there are two basic types of luggage on the market: hard-sided and soft-sided luggage. These two types of luggage differ primarily in the materials of which their sidewalls are made. Soft-sided luggage has sidewalls that are constructed of layers of fabric, soft rubber, or another flexible material. The sidewall material may be stiffened or stretched across a rigid or semirigid frame to form panels. Hard-sided luggage, on the other hand, has sidewalls that are made of a rigid or semirigid material, such as a metal, plastic, or wood. For example, whereas a soft-sided piece of luggage may use a woven nylon fabric for its sidewalls, a hard-sided piece of luggage may use a material like polycarbonate plastic for its sidewalls. Whether hard-sided or soft-sided, many modern pieces of luggage have integrated wheels and an integrated, telescoping handle. A piece of luggage that includes integrated wheels and a handle is often referred to as an upright roller bag.
Luggage is also commonly classified based on the configuration of its storage space. In a classic piece of luggage, the sidewalls and bottom of the piece provide most of the storage volume, while the top or cover panel typically has fairly little depth compared to the sidewalls and is hingedly connected to one of the sidewalls. However, a second type of luggage, called “clamshell” luggage, has gained in popularity. In a piece of clamshell luggage, there are two halves or sides of substantial depth that are hingedly connected to one another, typically along the bottom. In most cases, the two halves are of essentially equal depth, and are releasably attached to each other along the non-hinged sides by a zipper or other fasteners.
In many cases, the internal volume of a piece of luggage is open and undivided, although some pieces of luggage do include internal dividers or pockets, and most luggage includes straps or netting to prevent possessions from shifting during transport. Luggage that provides an open, undivided internal volume or compartment gives users the most flexibility, because possessions may be of any size, as long as they fit within the compartment, and can be arranged however the user chooses. However, luggage with an undivided internal compartment can be inconvenient because it can easily become disorganized, requiring the user to fully or partially unpack at his or her destination, or to hunt through the entire compartment of the luggage in order to find possessions. Luggage with internal compartments or dividers can ameliorate some of these problems, but usually at the expense of flexibility.